Two-dimensional coherent beam combination using circular or spiral diffraction grating

ABSTRACT

Examples of combining multiple laser beams into a single laser beam by using a circular or spiral diffraction grating are described. The multiple laser beams can be combined coherently or incoherently depending on the geometrical layout of the laser beams.

CROSS REFERENCE TO RELATED PATENT APPLICATION(S)

The present disclosure is a part of a Continuation application claimingthe priority benefit of U.S. Non-Provisional patent application Ser. No.15/432,442, filed on Feb. 14, 2017, which claims the priority benefit ofU.S. Provisional Patent Application No. 62/295,992, filed on Feb. 16,2016, the contents of which are incorporated by reference in theirentirety.

TECHNICAL FIELD

The present disclosure generally relates to the field of laser and, moreparticularly, to two-dimensional coherent combining of laser beams.

BACKGROUND

Unless otherwise indicated herein, the approaches described in thissection are not prior art to the claims in this application and are notadmitted as prior art by inclusion in this section.

The current demand for high power laser systems is growing in the marketplace and many techniques and methods of increasing laser power havebeen designed and developed for government and industrial applications.Increasing the brightness of a laser beam allows scaling laser power toa few hundred kilo-watts. There are two distinctive methods of scaling alaser beam such as coherent beam combining (CBC) and incoherent beamcombining (IBC). CBC is relatively difficult compared to the IBC beamcombining technique due to the phase lock requirements in the CBCtechnique.

Some of the advantages of the CBC technique include better beam quality,a narrow spectral bandwidth and high brightness compared to the IBCscheme. One of the major IBC methods is increasing brightness of thelaser beam by combining multiple beams of different wavelengths, calledwavelength beam combination (WBC), in a one-dimensional (1D) ortwo-dimensional (2D) configuration. There exist approaches thatdemonstrate a WBC beam combining technique in a 2D configuration usinglaser sources combined with a first-order grating stack. This WBCconcept trades high spatial brightness for relatively large spectralbandwidth by combing multiple bandwidths of the laser sources. In orderto improve the brightness in both dimensions a first-order grating stackis used to overlap horizontal and vertical dimensions of the opticalbeam to improve the brightness in both dimensions. During the WBCtechnique, a first and second grating are used to combine and improvehorizontal and vertical brightness of the laser sources respectively.The combined and improved laser output beam is an incoherent laser beamwith a relatively broad spectral bandwidth compared to each lasersource.

Also, a similar WBC approach is used exclusively in a fiber amplifierwith passive phase control. In order to achieve a single coherent beamcombining with a diffractive grating, it requires a feed-back system topassively lock the phase of each fiber amplifier. Still, using thismethod, this approach broadens the spectral bandwidth of the combinedbeam. As the number of combined laser sources increases the spectralbandwidth will grow too, making it more difficult to phase-lock alllaser sources.

The difficulty in designing a passive coherent beam combining techniquelays with the need to lock all phase and spectral overlap of lasersources that are being combined. Most all CBC techniques require afeedback system to passively or actively lock all phase of the lasersources. This would require a very complicated optical or electricalfeedback system.

Another difficulty in building a 2D coherent beam combining system isbundling together all laser sources in scaling up to a very high-powerlaser system. Typically, it is a geometrical constraint to mount alllaser sources in a compact form to coherently combine all laser sources.Currently there exists a 2D wavelength beam combining scheme using agrating stack that has two diffractive gratings combining a horizontaland vertical direction separately.

FIG. 9 is a perspective view of a prior art single-wavelength laser beamimpinging on a diffraction grating. Referring to FIG. 9, asingle-wavelength (monochrome) laser beam 1 impinges on a diffractiongrating 5 and creates a diffraction pattern of 0th order 4, 1st order 7and 2nd order 8. Diffraction grating 5 has a grating pattern of multiplea circular-shaped pattern (e.g., with multiple concentric rings) or aspiral-shape or pattern. Diffraction grating 5 projects perfect rings ofdiffractive patterns 4, 7 and 8 by the circular or spiral pattern of thegrating. The rings of the circular patterned grating or the spiral ofthe spiral patterned grating are an intrinsic property of diffractiongrating 5. In order to create a perfect ring of the diffracted patternthe laser beam 1 needs to impinge on the center of the circular orspiral pattern of the diffraction grating 5. The multiple rings causedby diffractive grating 5 are coherent light diffracted from the laserbeam 1. This means that the light beam 2 impinging on the center ofdiffractive grating 5 splits into three diffractive orders of the laserbeam 1 where these resultant beams 6 are in the same frequency andconstant phase with respect to each other. The coherent beamcharacteristic of the diffracted beam caused by the circular or spiralpattern of diffraction grating 5 only works with a laser beam 1 of asingle wavelength.

FIG. 10 is a projected side view of FIG. 9. FIG. 10 shows multiplediffracted orders of diffraction grating 5. The side view shows multiplecone-shaped rings are formed. This illustration shows that asingle-wavelength (monochrome) laser beam 1 can be diffracted to createthree different orders of diffraction patterns as an example. Thecircular patterned diffraction grating 5 generates diffracted rings of asingle-wavelength laser beam 1 as shown in FIG. 10 where it has a brightspot at the center of the patterned rings. However, the spiral patterneddiffraction grating 5 generates a dark spot at the center of ringssimilar to a ‘donut’ hole shape. The ring patterns 4, 7 and 8 of thediffracted laser beams 6 can be designed or changed by using differentpatterns in the diffraction grating 5 or changing the gratingparameters.

FIG. 11 is a perspective view of a prior art multiple-wavelength laserbeam impinging on a diffraction grating. Referring to FIG. 11, amultiple-wavelength laser beam 11 impinges on the diffraction grating 5where each wavelength of laser beam 11 will generate multiple rings ofdiffraction orders. For example, if the multiple-wavelength laser beam11 contains two distinctive wavelengths of λ1 and λ2 of laser beam 12 isimpinging on the diffraction grating 5 and each wavelength of λ1 and λ2will generate multiple rings of diffraction orders of 0th, 1st and2^(nd) orders. The λ1 wavelength of the laser beam 11 will create the0th order of spot 20, the 1st order of ring 19 and the 2nd order of ring17. The λ2 wavelength of the laser beam 11 will create the 0th order ofspot 20, the 1st order of ring 14 and the 2nd order of ring 18 where thewavelength of λ1 is shorter than λ2. In this case the diffractive ringsof the wavelength λ1 is coherent to each other and it is incoherent tothe other wavelength λ2. The multiple-wavelength laser beam 11 cancreate multiple orders of rings that are coherent to the same wavelengthand incoherent to different wavelengths. The wavelength separationtechnique of using circular or spiral patterned diffraction gratings canbe applied to optical signal transmission such as awavelength-division-multiplex (WDM). Alternatively, it can be used tocombine multiple wavelengths into a single optical beam using thereverse process.

FIG. 12 is a projected side view of FIG. 11. FIG. 12 shows multiplediffracted orders of the multiple-wavelength laser beam 11 diffracted bythe circular or spiral pattern of the diffraction grating 5. The sideview shows that multiple cone-shaped rings are formed bymultiple-wavelength laser beam 11. This illustration shows that amultiple-wavelength laser beam 11 can be diffracted to create threedifferent orders of diffraction patterns for each wavelength of two,namely λ1 and λ2. The circular patterned diffraction grating 5 generatesdiffracted rings of multiple-wavelength laser beam 11 as shown in FIG.11 where it has a bright spot of the mixed laser beam 11 of wavelengthof λ1 and λ2 at the center, and the multiple orders of patterned ringshave a distinctive wavelength of λ1 or λ2. However, the spiral patterneddiffraction grating generates a dark spot at the center of thediffracted rings like a ‘donut’ hole shape. The ring patterns of thediffracted laser beams 14, 17, 18, 19 and 20 can be designed or changedby different patterns of the diffraction grating 11 or its gratingparameters.

SUMMARY

The following summary is illustrative only and is not intended to belimiting in any way. That is, the following summary is provided tointroduce concepts relating to a heat sink for thermal management in anelectronic apparatus. Select embodiments of the novel and non-obvioustechnique are further described below in the detailed description. Thus,the following summary is not intended to identify essential features ofthe claimed subject matter, nor is it intended for use in determiningthe scope of the claimed subject matter.

In one aspect, a method of coherently combining a plurality of opticalbeams may involve arranging a plurality of single-wavelength lasers in aring-shaped pattern. The method may also involve energizing theplurality of single-wavelength lasers to emit the plurality of opticalbeams such that the plurality of optical beams impinge on a centralregion of a diffractive element to combine the optical beams to form asingle laser beam. The single laser beam may resonate through a lasercavity formed by a partial reflector and the plurality ofsingle-wavelength lasers.

In another aspect, a method of incoherently combining a plurality ofoptical beams may involve arranging a plurality of multiple-wavelengthlasers in a plurality of ring-shaped patterns. The method may alsoinvolve energizing the plurality of multiple-wavelength lasers to emitthe plurality of optical beams such that the plurality of optical beamsimpinge on a central region of a diffractive element to combine theoptical beams to form a single laser beam. The single laser beam mayresonate through a laser cavity formed by a partial reflector and theplurality of multiple-wavelength lasers.

In one aspect, a system for coherently combining a plurality of opticalbeams may include a plurality of single-wavelength lasers arranged in aring-shaped pattern and a diffractive element. When energized, theplurality of single-wavelength lasers may emit the plurality of opticalbeams such that the plurality of optical beams impinge on a centralregion of the diffractive element to combine the optical beams to form asingle laser beam. The single laser beam may resonate through a lasercavity formed by a partial reflector and the plurality ofsingle-wavelength lasers.

In another aspect, a system for incoherently combining a plurality ofoptical beams may include a plurality of multiple-wavelength lasersarranged in a plurality of ring-shaped patterns and a diffractiveelement. When energized, the plurality of multiple-wavelength lasers mayemit the plurality of optical beams such that the plurality of opticalbeams impinge on a central region of the diffractive element to combinethe optical beams to form a single laser beam. The single laser beam mayresonate through a laser cavity formed by a partial reflector and theplurality of multiple-wavelength lasers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of the present disclosure. The drawings illustrate embodiments ofthe disclosure and, together with the description, serve to explain theprinciples of the disclosure. It is appreciable that the drawings arenot necessarily in scale as some components may be shown to be out ofproportion than the size in actual implementation in order to clearlyillustrate the concept of the present disclosure.

FIG. 1 is a perspective view of combining plural laser beams into asingle laser beam using a diffraction grating in a transmissive mode inaccordance with an embodiment of the present disclosure.

FIG. 2 is a perspective view of combining plural laser beams into asingle laser beam using a diffraction grating in a reflective mode inaccordance with an embodiment of the present disclosure.

FIG. 3 is a projected side view of FIG. 2.

FIG. 4 is a perspective view of passive coherent beam combining ofsingle-wavelength laser beams using an intra-cavity laser system alongwith a transmissive diffraction grating in accordance with an embodimentof the present disclosure.

FIG. 5 is a projected side view of FIG. 4.

FIG. 6 is a perspective view of passive coherent beam combining ofsingle-wavelength laser beams using an intra-cavity laser system alongwith a reflective diffraction grating in accordance with an embodimentof the present disclosure.

FIG. 7 is a projected side view of FIG. 6.

FIG. 8 is a perspective view of incoherent beam combining ofmultiple-wavelength laser beams using a transmissive diffraction gratingin accordance with an embodiment of the present disclosure.

FIG. 9 is a perspective view of a prior art single-wavelength laser beamimpinging on a diffraction grating.

FIG. 10 is a projected side view of FIG. 9.

FIG. 11 is a perspective view of a prior art multiple-wavelength laserbeam impinging on a diffraction grating.

FIG. 12 is a projected side view of FIG. 11.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Overview

A new approach for 2D coherent beam combining scheme is needed tosimplify the geometrical design and self-feedback mechanism in order tobuild a compact and large scalable high-power laser system. To design ascalable 2D coherent beam combining scheme a circular or spiraldiffraction grating is used to combine all laser sources in anintra-cavity laser design. In this case a circularly positioned lasersources project their beams on to the center of the circular or spiraldiffraction grating to form a single output laser beam. This approacheliminates the double diffraction grating scheme used in the existingapproach and the circular or spiral grating provides a 2D coherent beamcombine function. Unlike other diffractive grating beam combiningmethods, the circular or spiral grating provides passive phase lockingof all laser sources in single piece operation. Otherwise, the verticaland horizontal axis of the laser beam has to be combined by two separategratings.

The circular or spiral diffraction grating allows combining all lasersources into a single coherent beam and passive phase locking is alsopossible. The combined laser beam has a similar or better spectralbandwidth than the laser source. Unlike the WBC process, which increasesthe spectra bandwidth proportion to the number of the laser sources thatare combined. The coherent beam of the circular or spiral diffractiongrating provides much better brightness and beam quality than the WBCprocess.

Illustrative Implementations

FIG. 1 is a perspective view of combining plural laser beams into asingle laser beam using a diffraction grating in a transmissive mode inaccordance with an embodiment of the present disclosure. The exampleillustrated in FIG. 1 shows combining six lasers 21 into one laser beam24 using the diffraction grating 5 working in a transmissive (ortransparent) mode. The lasers 21 are placed or otherwise arranged in aring pattern 30 of the diffraction order illustrated in FIG. 9. Thisbeam combining concept is the reverse of the process of thatdemonstrated in FIG. 9. The lasers 21 are placed in one of thediffraction rings in FIG. 9 and the laser beam 22 emitted by each laser21 is projected in a direction 23 to a central region of the diffractiongrating 5. Due to the diffractive angle a1 of the diffraction grating 5,all laser beams 22 will overlap into a single laser beam 24. In thiscase the wavelength of all lasers 21 matches with each other and adistance from the diffraction grating 5 to each of the lasers 21 issubstantially equaled to each other in order to maintain coherent beamcharacteristics. That is, the multiple lasers 21 can be seen as beingplaced on a horizontal plane so as to be equal-distant from the centerof diffraction grating 5. The single laser beam 24 has coherentcharacteristics of beam propagation due to same frequency and constantphase difference. In order to obtain a zero-phase difference in alllasers 21, each phase factor of the lasers 21 can be adjusted to match‘in-phase’ status for maximum brightness. The cone angle, a1, is matchedwith the diffractive angles of the diffraction grating 5 with themonochrome wavelength of the lasers 21. The lasers 21 can be any lasersource that can produce a sufficiently narrow spectrum of a singlewavelength. For instance, lasers 21 may include semiconductor lasers,fiber lasers, DPSS (diode pumped solid state) lasers, gas lasers, liquidlasers, or any combination thereof.

FIG. 2 is a perspective view of combining plural laser beams into asingle laser beam using a diffraction grating in a reflective mode inaccordance with an embodiment of the present disclosure. The exampleillustrated in FIG. 2 shows combining six lasers 31 into one laser beam34 using a diffraction grating 35 working in a reflective mode. Thelasers 31 are placed or otherwise arranged in a ring pattern 30 of thediffraction order illustrated in FIG. 9. The beam combining concept is areversed process of that demonstrated in FIG. 9. The lasers 31 areplaced in one of the diffraction rings in FIG. 9 as reflectiveconfiguration and the laser beam 32 of each laser 31 is projected in adirection 33 to a central region of the diffraction grating 35. Due tothe diffractive angle a2 of the diffraction grating 35, all lasers 31will overlap into a single laser beam 34. In this case the wavelength ofall lasers 31 matches with each other and a distance from thediffraction grating 35 to each of the lasers 31 is substantially equalto each other in order to maintain coherent beam characteristics. Thelaser beam 34 has coherent characteristics of beam propagation due tosame frequency and constant phase difference. In order to obtain azero-phase difference in all lasers 31, each phase factor of the lasers31 can be adjusted to match ‘in-phase’ status for maximum brightness.The cone angle, a2, is matched with the diffractive angles of thediffraction grating 35 with the monochrome wavelength of the lasers 31.The lasers 31 can be any laser source that can produce a sufficientlynarrow spectrum of single wavelength. For instance, lasers 31 mayinclude semiconductor lasers, fiber lasers, DPSS lasers, gas lasers,liquid lasers, or any combination thereof.

FIG. 3 is a projected side view of FIG. 2. FIG. 3 shows the beam 32 ofeach of the lasers 31 propagating onto the center of the diffractiongrating 35. Each beam 32 is unidirectional (in the direction 33) andparallel collimated onto the diffraction grating 35. If the beam 32 isnot sufficiently parallel collimation of the laser 31, the beam qualityof the output beam 34 may be degraded. The cone angle of a2 is the sameas the diffraction angle of the diffraction grating 35.

FIG. 4 is a perspective view of passive coherent beam combining ofsingle-wavelength laser beams using an intra-cavity laser system alongwith a transmissive diffraction grating in accordance with an embodimentof the present disclosure. The example illustrated in FIG. 4 showspassive coherent beam combining of single-wavelength lasers 41 using anintra-cavity laser system along with a transmissive diffractive grating5. The beam combining technique presented in FIG. 1 is applied here,building an intra-cavity laser system, and the diffraction grating 5 hasa circular pattern (e.g., with multiple concentric rings) or a spiralpattern (e.g., with a spiraling curve). All lasers 41 are placed orotherwise arranged on the 1st order of diffracted ring pattern of thediffraction grating 5 and the beams 42 emitted by lasers 41 are focusedonto a central region of the diffraction grating 5. At least a portionof the refracted beams 49 on a center axis 46 of the diffraction grating5 is reflected back (circulated) to the diffraction grating 5 by a highreflectance mirror 48 and the reflected beam is fed into the diffractiongrating 5. Some of circulating beams 49 come out through the partialreflector (output coupler) 47 as a laser beam 44. Each laser 41 in thering 50 is designed to work as an intra-cavity laser formed by the highreflector 48, the diffraction grating 5 and the partial reflector 47.All lasers 41 resonate between the high reflector 48 and the partialreflector 47. The diffraction grating 5 is used to combine laser beamsof all lasers 41 into a laser cavity built between the partial reflector47 and the lasers 41.

FIG. 5 is a projected side view of FIG. 4. FIG. 5 shows that laser beams42 emitted by lasers 41 are projected onto the transmissive diffractiongrating 5 and some of the laser beams (42) are diffracted to the partialreflector 47. Some of the beams 49 are reflected by the partialreflector 47 and returned back to the transmissive diffraction grading5. The beams 49 can diffract to lasers 41 or reflect by the highreflector 48 back to the laser cavity. As the laser beams circulatearound the resonator, they eventually come out through the partialreflector 47 as a coherent laser beam 44. The lasers 41 have a singlewavelength with a diffraction angle of a4 that allows each emitted beam42 to diffract into a respective beam 49 and circulate in the lasercavity comprised of the partial reflector 47, the high reflector 48 andthe respective laser 41. This innovative intra-cavity laser design willresult in a coherent combined beam being generated by the lasers 41. Thelasers 41 can be any laser source that can produce a sufficiently narrowspectrum of single wavelength. For instance, lasers 41 may includesemiconductor lasers, fiber lasers, DPSS lasers, gas lasers, liquidlasers, or any combination thereof.

FIG. 6 is a perspective view of passive coherent beam combining ofsingle-wavelength laser beams using an intra-cavity laser system alongwith a reflective diffraction grating in accordance with an embodimentof the present disclosure. The example illustrated in FIG. 6 showspassive coherent beam combining of single-wavelength lasers 51 using anintra-cavity laser system along with reflective diffractive grating 35.The beam combining technique presented in FIG. 2 is applied here,building an intra-cavity laser system, and the diffraction grating 35has a circular pattern (e.g., with multiple concentric rings) or spiralpattern (e.g., with a spiraling curve). All lasers 51 are placed orotherwise arranged on the 1st order of diffracted ring pattern of thediffraction grating 35, and the beams 52 emitted by lasers 51 in adirection 53 are focused onto a central region of the diffractiongrating 35. A diffracted beam 54 of the emitted beams 52 is on a centeraxis 56 of the diffraction grating 35, and some of the beam 54 isreflected by the partial reflector 58 to come out as a single laser beam54 in a direction 56. The beams 52 are circulated between the lasers 51and the partial reflector 58, and the beams 52 comes out through thepartial reflector (output coupler) 58. Each laser 51 in the ring 60 isdesigned to work as an intra-cavity laser formed by the diffractiongrating 35 and the partial reflector 58. The reflective diffractiongrating 35 has a function of coherently combining beams 52 emitted bylasers 51 into a single beam 54 in a single wavelength and narrowwavelength bandwidth compared to other beam combining techniques.

FIG. 7 is a projected side view of FIG. 6. FIG. 7 shows that laser beams52 emitted by all lasers 51 are projected onto the reflectivediffraction grating 35 and the laser beams 52 are diffracted by thediffraction grating 35 to the partial reflector 58. Some of the beams 52are reflected on the partial reflector 58 and then returned back to thelasers 51 by the reflective diffraction grading 35. The beam 54 passesthrough the partial reflector 58, which acts to coherently combine alllaser beams 52. Each beam 52 is angled to match with a diffractive angleof the circular or spiral pattern of the diffraction grating 35 to comeout on the center axis 56 of the diffraction grating 35. The partialreflector (output coupler) 58 is placed on the center axis 56 of thediffraction grating 35 to build an intra-cavity laser resonator for thelasers 51. The diffraction grating 35 with one or more circular orspiral patterns allows combing multiple laser beams 52 into a singlecoherent beam 54.

FIG. 8 is a perspective view of incoherent beam combining ofmultiple-wavelength laser beams using a transmissive diffraction gratingin accordance with an embodiment of the present disclosure. The exampleillustrated in FIG. 8 shows incoherent beam combining of multiplewavelengths using a transmissive diffraction grating 5. The beamcombining concept is the reverse process of a multiple wavelength laserbeam that is diffracted by a circular or spiral patterned transmissivegrating as illustrated in FIG. 11. The basic concept is where eachdifferent wavelength of collinear laser beams impinging on the center ofthe diffractive grating will generate multiple orders of diffractionrings. For instance, if laser beams with two different wavelengths areplaced in two separate diffraction rings grouped by the respectivewavelength, then all laser beams in each ring can be combined into asingle laser beam mixed with two separate wavelengths. However, thecombined laser beam cannot be a coherent laser beam due to the twoseparate rings with two different wavelengths in this example. FIG. 8shows two separate rings 70 and 71 of laser placement. A first and outerring 70 contains multiple lasers 61 that are disposed or otherwisearranged along the ring 70. A second and inner ring 71 contains multiplelasers 81 that are disposed or otherwise arranged along the ring 71. Thelasers 61 and the lasers 81 have different wavelengths matched withdifferent diffraction angles of the diffraction grating 5, and thisallows the diffraction grating 5 to diffract each of the laser beams 62and 82, emitted by lasers 61 and lasers 81 in the rings 70 and 71,respectively, into a single laser beam 64. A part of the beam 64 will bereflected by a partial reflector 47 and a part of the beam 64 will betransmitted as a laser beam 64 out of the partial reflector 47 along acenter axis 66 of the diffraction grating 5. The beam combining processof using a circular or spiral pattern of the diffractive grating 5 inthe intra-cavity design of laser system will generate a coherent beam ofeach wavelength, and the combined beam becomes incoherent as the mixedbeam 64.

Highlight of Select Features

In view of the above, select features in accordance with the presentdisclosure are highlighted below.

In one aspect, a method of coherently combining a plurality of opticalbeams may involve arranging a plurality of single-wavelength lasers in aring-shaped pattern. The method may also involve energizing theplurality of single-wavelength lasers to emit the plurality of opticalbeams such that the plurality of optical beams impinge on a centralregion of a diffractive element to combine the optical beams to form asingle laser beam. The single laser beam may resonate through a lasercavity formed by a partial reflector and the plurality ofsingle-wavelength lasers.

In some implementations, the single-wavelength lasers may include atleast one array of semiconductor diode lasers, fiber lasers, solid-statelasers, gas lasers, or a combination thereof.

In some implementations, a spectral bandwidth of the optical beamsemitted by the single-wavelength lasers may be equal to or less than 5nanometers.

In some implementations, the diffractive element may include areflective grating or a transmissive grating.

In some implementations, the diffractive element may include a circulargrating configured to generate one or more ring-like diffractivepatterns. In some implementations, the one or more ring-like diffractivepatterns may include a continuous or discrete form of one or morering-like shapes. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the single-wavelength lasers.

In some implementations, the diffractive element may include a spiralgrating configured to generate one or more ring-like diffractivepatterns. In some implementations, the one or more ring-like diffractivepatterns may include a continuous or discrete form of one or morering-like shapes. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the single-wavelength lasers.

In another aspect, a method of incoherently combining a plurality ofoptical beams may involve arranging a plurality of multiple-wavelengthlasers in a plurality of ring-shaped patterns. The method may alsoinvolve energizing the plurality of multiple-wavelength lasers to emitthe plurality of optical beams such that the plurality of optical beamsimpinge on a central region of a diffractive element to combine theoptical beams to form a single laser beam. The single laser beam mayresonate through a laser cavity formed by a partial reflector and theplurality of multiple-wavelength lasers.

In some implementations, the multiple-wavelength lasers may include atleast one array of semiconductor diode lasers, fiber lasers, solid-statelasers, gas lasers, or a combination thereof.

In some implementations, each of the optical beams may have at least twoseparate wavelengths, with each of the at least two separate wavelengthshaving a spectral bandwidth equal to or less than 5 nanometers.

In some implementations, the diffractive element may include areflective grating or a transmissive grating.

In some implementations, the diffractive element may include a circulargrating configured to generate one or more ring-like diffractivepatterns at a plurality of wavelengths. In some implementations, the oneor more ring-like diffractive patterns may include a continuous ordiscrete form of one or more ring-like shapes at the plurality ofwavelengths. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the plurality of multiple-wavelength lasers.

In some implementations, the diffractive element may include a spiralgrating configured to generate one or more ring-like diffractivepatterns at a plurality of wavelengths. In some implementations, the oneor more ring-like diffractive patterns may include a continuous ordiscrete form of one or more ring-like shapes at the plurality ofwavelengths. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the plurality of multiple-wavelength lasers.

In one aspect, a system for coherently combining a plurality of opticalbeams may include a plurality of single-wavelength lasers arranged in aring-shaped pattern and a diffractive element. When energized, theplurality of single-wavelength lasers may emit the plurality of opticalbeams such that the plurality of optical beams impinge on a centralregion of the diffractive element to combine the optical beams to form asingle laser beam. The single laser beam may resonate through a lasercavity formed by a partial reflector and the plurality ofsingle-wavelength lasers.

In some implementations, the single-wavelength lasers may include atleast one array of semiconductor diode lasers, fiber lasers, solid-statelasers, gas lasers, or a combination thereof.

In some implementations, a spectral bandwidth of the optical beamsemitted by the single-wavelength lasers may be equal to or less than 5nanometers.

In some implementations, the diffractive element may include areflective grating or a transmissive grating.

In some implementations, the diffractive element may include a circulargrating configured to generate one or more ring-like diffractivepatterns. In some implementations, the one or more ring-like diffractivepatterns may include a continuous or discrete form of one or morering-like shapes. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the single-wavelength lasers.

In some implementations, the diffractive element may include a spiralgrating configured to generate one or more ring-like diffractivepatterns. In some implementations, the one or more ring-like diffractivepatterns may include a continuous or discrete form of one or morering-like shapes. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the single-wavelength lasers.

In another aspect, a system for incoherently combining a plurality ofoptical beams may include a plurality of multiple-wavelength lasersarranged in a plurality of ring-shaped patterns and a diffractiveelement. When energized, the plurality of multiple-wavelength lasers mayemit the plurality of optical beams such that the plurality of opticalbeams impinge on a central region of the diffractive element to combinethe optical beams to form a single laser beam. The single laser beam mayresonate through a laser cavity formed by a partial reflector and theplurality of multiple-wavelength lasers.

In some implementations, the multiple-wavelength lasers may include atleast one array of semiconductor diode lasers, fiber lasers, solid-statelasers, gas lasers, or a combination thereof.

In some implementations, each of the optical beams may have at least twoseparate wavelengths, with each of the at least two separate wavelengthshaving a spectral bandwidth equal to or less than 5 nanometers.

In some implementations, the diffractive element may include areflective grating or a transmissive grating.

In some implementations, the diffractive element may include a circulargrating configured to generate one or more ring-like diffractivepatterns at a plurality of wavelengths. In some implementations, the oneor more ring-like diffractive patterns may include a continuous ordiscrete form of one or more ring-like shapes at the plurality ofwavelengths. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the plurality of multiple-wavelength lasers.

In some implementations, the diffractive element may include a spiralgrating configured to generate one or more ring-like diffractivepatterns at a plurality of wavelengths. In some implementations, the oneor more ring-like diffractive patterns may include a continuous ordiscrete form of one or more ring-like shapes at the plurality ofwavelengths. In some implementations, the one or more ring-likediffractive patterns may match with a diffractive angle of thediffractive element at the plurality of multiple-wavelength lasers.

ADDITIONAL NOTES AND CONCLUSION

The herein-described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely examples, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

Further, with respect to the use of substantially any plural and/orsingular terms herein, those having skill in the art can translate fromthe plural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims, e.g., bodies of theappended claims, are generally intended as “open” terms, e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc. It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an,” e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more;” the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number, e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations. Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention, e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc. In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention, e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc. It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A system capable of coherently combining aplurality of optical beams, comprising: a plurality of single-wavelengthlasers arranged in a ring-shaped pattern; and a diffractive element,wherein, when energized, the plurality of single-wavelength lasers emitthe plurality of optical beams such that the plurality of optical beamsimpinge on a central region of the diffractive element to combine theoptical beams to form a single laser beam, wherein the single laser beamresonates through a laser cavity formed by a partial reflector and theplurality of single-wavelength lasers, and wherein the diffractiveelement comprises a circular grating configured to generate one or morering-like diffractive patterns.
 2. The system of claim 1, wherein thesingle-wavelength lasers comprise at least one array of semiconductordiode lasers, fiber lasers, solid-state lasers, gas lasers, or acombination thereof.
 3. The system of claim 1, wherein a spectralbandwidth of the optical beams emitted by the single-wavelength lasersis equal to or less than 5 nanometers.
 4. The system of claim 1, whereinthe diffractive element comprises a reflective grating or a transmissivegrating.
 5. The system of claim 1, wherein the one or more ring-likediffractive patterns comprise a continuous or discrete form of one ormore ring-like shapes.
 6. The system of claim 1, wherein the one or morering-like diffractive patterns match with a diffractive angle of thediffractive element at the single-wavelength lasers.
 7. A system capableof coherently combining a plurality of optical beams, comprising: aplurality of single-wavelength lasers arranged in a ring-shaped pattern;and a diffractive element, wherein, when energized, the plurality ofsingle-wavelength lasers emit the plurality of optical beams such thatthe plurality of optical beams impinge on a central region of thediffractive element to combine the optical beams to form a single laserbeam, wherein the single laser beam resonates through a laser cavityformed by a partial reflector and the plurality of single-wavelengthlasers, and wherein the diffractive element comprises a spiral gratingconfigured to generate one or more ring-like diffractive patterns. 8.The system of claim 7, wherein the one or more ring-like diffractivepatterns comprise a continuous or discrete form of one or more ring-likeshapes.
 9. The system of claim 7, wherein the one or more ring-likediffractive patterns match with a diffractive angle of the diffractiveelement at the single-wavelength lasers.